This invention relates to a swimmer's snorkel to be used during swimming.
Japanese Utility Model Publication No. 1974-33039 discloses a snorkel in which a mouthpiece has on its top a part to be held in a swimmer's mouth and on its bottom, opposed to the top, through-holes for drainage, and is provided on the outside of the bottom with a non-return valve openably closing these through-holes. When a swimmer rises toward the water surface until the snorkel is partially exposed above the water surface, a quantity of water corresponding to the quantity of water remaining in a portion of the snorkel now exposed above the water surface is forced out from the snorkel through the non-return valve.
U.S. Pat. No. 4,834,084 discloses a snorkel in which an inner space of a mouthpiece in the form of a substantially U-shaped tube is partitioned into upper and lower spaces by a baffle plate extending horizontally inward from a tubular wall. A means to be held in a swimmer's mouth is formed above the baffle plate and a horizontally extending non-return valve is provided below the baffle plate and adapted to be opened or closed. The swimmer's exhalation strikes the baffle plate and does not act directly upon the non-return valve in the case of this snorkel. Therefore, the quantity of water remaining within the snorkel can be rapidly expelled through an upper opening of the snorkel by vigorous exhalation of the swimmer without opening the non-return valve unintentionally.
As noted above, the snorkel disclosed in U.S. Pat. No. 4,834,084 has a baffle plate extending inward from a tubular wall of the mouthpiece. Since the mouthpiece is generally molded by injection molding of thermoplastic material, a set of male and female dies for molding the baffle plate tends to be more complicated and a molding cycle must be often extended, particularly when the mouthpiece is in a U-shaped tubular form having therein the baffle plate. Manufacturing cost is inevitably increased in this case.